"noon" is not a recognized keyword, and you need to include the keyword "to" when constructing commands with specific times.
try "radd today at 12pm to call Jack James"
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From your log file, it seems that you have an unsupported scripting addition (/Library/ScriptingAdditions/QXPScriptingAdditions.osax). It shouldn't affect this workflow, but it might trip something up, so you might want to delete it.
It also looks like your cache file might be corrupted, I've built a new version of the workflow which will check for this and recreate the file as needed.
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I've updated to the latest GM (thanks for that) so I should be in sync with what you're seeing (for the record, they haven't fixed the osascript bug, so it'll still be slow). In addition, Alfred notifications don't seem to be working at all in this latest build of OS X
Anyway, I've run into the same problem as you with the cache process completely crashing and corrupting the cache file. It seems that another bug has been introduced since the last GM (sigh), meaning it's no longer possible to create arrays/lists in plists via System Events.
I've made a workaround for this which seems to work (and hopefully won't break it for everyone on other versions of OS X…), download the latest version.